wrote: "We're always here for you and love you guys so much."
Channing Tatum commented: "Sending so much love to you right now," while added: "Chrissy & John, I am so sorry to hear this news. Sending you all love. Will say a prayer for Jack tonight. Your guardian angel."
Gabrielle Union added: "We love you guys so much and we will be here for whatever yall need. Always."
Chrissy has been and previously told her Instagram followers: "I was always, always bleeding.
"I'm about halfway through pregnancy and the blood has been going on for a little less than a month.
"More than a period, girls, and definitely not spotting."
On September 24, Chrissy announced that her latest cook book would be postponed indefinitely due to her "high-risk" pregnancy.
She added that her third pregnancy was unexpected and she "didn't think" she was able to get pregnant naturally, as her two other children were conceived through IVF treatments.
She previously said that she didn't think she could get pregnant naturally Credit: PA:Press Association